The present invention relates to vehicle emissions testing, and, more particularly, to a device that notifies a vehicle operator that the vehicle is ready for an emissions inspection.
Recognizing the adverse effects that vehicle emissions have on the environment, the 1990 Clean Air Act requires that communities in geographic regions having high levels of air pollution implement Inspection and Maintenance (“I/M”) programs for vehicles in the particular geographic regions. Such I/M programs are intended to improve air quality by periodically testing the evaporative and exhaust emissions control systems of vehicles in the community and ensuring their proper operation and maintenance. By ensuring that the evaporative and exhaust emissions control systems of vehicles are operational and properly maintained, air pollution resulting from vehicle emissions in the geographic region should be drastically reduced.
I/M programs in the United States typically employ some method of “tailpipe” testing as the primary means of inspection. Although there are several variations of common tailpipe testing, the core function of tailpipe testing remains the same. First, a probe is attached to, or inserted into, the tailpipe of the vehicle being tested to collect exhaust as the engine of the vehicle is running. The collected exhaust is then introduced into a series of gas analyzers in order to determine its composition. Finally, a report of the amount of measured pollutants is generated.
In 1992, the California Air Resources Board (CARB) proposed regulations for the monitoring and evaluation of a vehicle's emissions control system through the use of second-generation on-board diagnostics (“OBDII”). (See California Code of Regulations, Title 13, 1968.1—Malfunction and Diagnostic Systems Requirements—1994 and subsequent model year passenger cars, light-duty trucks, and medium-duty vehicles with feedback fuel control systems.) These regulations were later adopted by the United States Environmental Protection Agency. (See Environmental Protection Agency, 40 C.F.R. Part 86—Control of Air Pollution From New Motor Vehicles and New Motor Vehicle Engines; Regulations Requiring On-Board Diagnostic Systems on 1994 and Later Model Year Light-Duty Vehicles and Light-Duty Trucks.) As a result, OBDII systems were required to be phased in beginning in 1994, and by 1996, almost all light-duty, gasoline-powered motor vehicles in the United States were required to have OBDII systems.
In general, through the use of OBDII systems, the emissions control system of a vehicle is constantly monitored, with a “check engine” light or Malfunction Indicator Light (MIL) on the dashboard of the vehicle being illuminated to inform the operator of a problem with the emissions control systems. The OBDII system is commonly interrogated as part of I/M programs to ensure it is functioning properly.
Discussing now the more specific operational details, OBDII systems are designed to monitor certain emissions control systems, i.e., groupings of related vehicle emissions components, to ensure they are functioning properly. Each such emissions control system is evaluated by a “monitor,” which also may be referred to as an “OBDII monitor” or a “readiness monitor.” CARB designates eleven monitors that the OBDII system of a vehicle may be required to evaluate:
TABLE AMONITORTYPEFuel Metering/TrimContinuousMisfireContinuousComprehensiveContinuousComponentAir ConditioningUnsupportedCatalyst HeaterUnsupportedCatalystNon-continuousOxygen SensorNon-continuousOxygen Sensor HeaterNon-continuousEvaporative EmissionsNon-continuousControl SystemSecondary AirNon-continuousExhaust Gas RecirculationNon-continuous
As indicated in Table A, the first three monitors are “continuous” in that evaluation of the particular emissions control system is ongoing at any time the vehicle engine is operating. For this reason, these three monitors are always reported by the OBDII system as being “ready,” meaning that the system has been evaluated. In this regard, it is important to recognize that a status of “ready” does not mean that the particular emissions control system is operating properly, but only that the system has been evaluated. If a particular vehicle emissions system has been evaluated, and a fault is found with the system, the check engine light or MIL will be illuminated.
Referring still to Table A, although identified in the applicable regulations, the air conditioning and catalyst heater monitors are not included in most vehicles and are therefore reported by the OBDII system as “unsupported.”
Finally, the remaining six monitors are characterized as “non-continuous” because if the vehicle supports them, functionality of the particular emissions control system can only be evaluated after the vehicle has been operating for a predetermined time period or until certain conditions are satisfied. Accordingly, a non-continuous monitor will be reported by the OBDII system as “not ready” until the predetermined time period has elapsed or the certain conditions have been satisfied. For example, assuming a non-continuous monitor is supported, the monitor will have a status of “not ready” when the vehicle is brand new (since the monitor has not yet had an opportunity to evaluate the emissions control system), if the battery has been disconnected for a period of time (such that computer memory is cleared), or if a technician performs specific operations on the OBDII system. After the vehicle has been operated until the predetermined time period has elapsed or the certain conditions have been satisfied, each monitor will evaluate its emissions control system, and the status of each monitor will then be reported as “ready.” The status continues to be reported as “ready” until reset by a technician or the battery of the vehicle is disconnected.
For example, the catalyst monitor evaluates whether the catalyst is functioning properly. This is generally accomplished through the use of two oxygen sensors, one upstream of the catalyst and one downstream of the catalyst. On a properly operating vehicle, the engine will vary from operating slightly lean (excess oxygen) to slightly rich (excess fuel). A common three-way catalyst, a catalyst that reduces the levels of hydrocarbons, carbon monoxide, and oxides of nitrogen, captures and stores the excess oxygen in the exhaust during the slightly lean periods, and then uses that oxygen during the periods of slightly rich operation to oxidize the hydrocarbons to carbon dioxide and water and to oxidize the carbon monoxide to carbon dioxide. Therefore, if a catalyst is functioning properly, the oxygen sensor upstream of the catalyst should measure a fluctuation in the oxygen content in the exhaust, but the downstream oxygen sensor should measure a much lower fluctuation in the oxygen content in the exhaust (since the oxygen is being absorbed by the catalyst and then converted into other molecules before passing the downstream oxygen sensor). If, however, the upstream and downstream sensors measure the same fluctuation in the oxygen content in the exhaust gas, it is an indication that the catalyst is not storing the excess oxygen and is therefore probably not oxidizing the hydrocarbons and carbon monoxide. Accordingly, the OBDII system may activate the check engine light to notify the vehicle operator that there is a problem with this emissions control system.
However, the catalyst functions properly only under specific conditions, and thus, the OBDII catalyst monitor often cannot immediately evaluate the catalyst after the OBDII memory is cleared and the catalyst monitor is reset to “not ready.” For instance, if the catalyst is cold, or if one of the oxygen sensors is not functioning properly, then the system cannot evaluate the catalyst function. Until the catalyst is in condition to be evaluated, the catalyst monitor will report a status of “not ready.” Once the appropriate conditions have been satisfied, the catalyst is evaluated, and the catalyst monitor is reported as “ready.”
In the past, I/M programs have often included under-hood visual and functional inspections of emissions control components combined with tailpipe emissions tests to determine if the emissions control systems of a vehicle are functioning properly. However, in recent years, an increasing number of I/M programs have been inspecting 1996 and newer vehicles by using electronic interrogation of the OBDII system to determine if the emissions control systems of a vehicle are functioning properly. Such testing is described in detail in “Performing Onboard Diagnostic System Checks as Part of a Vehicle Inspection and Maintenance Program,” EPA 420-R-01015 (June 2001), a report that is incorporated herein in its entirety by this reference.
However, if the battery of a vehicle is disconnected for a period of time, the OBDII system memory is cleared. If there was a fault previously identified by the OBDII system that caused the MIL to be illuminated, it will also be cleared. If the vehicle is tested in an I/M program via the OBDII system shortly after having the battery disconnected, the OBDII system may now appear not to have a problem because the OBDII system may not have had a chance to find the fault again before the I/M OBDII emissions inspection.
Furthermore, I/M program regulations typically require service technicians to clear the OBDII memory after repairs are performed. This is done so that when the OBDII system of the vehicle is checked after the repair to determine if the problem has been appropriately remedied, it is clear if the monitor for the system that was repaired has run and checked the repaired system. Again, if a particular system has been evaluated, it will be reported as “ready.” If it has not been evaluated, it will be reported as “not ready.”
Because unscrupulous vehicle operators, recognizing that there is a problem with an emissions control system because the MIL is illuminated, could attempt to conceal a known defect by disconnecting the battery to clear the OBDII system memory, I/M programs require a check of the readiness monitors to verify that the OBDII system has evaluated the emissions control systems. Because of the check for readiness, if the battery was disconnected just before the test to clear an illuminated MIL, various monitors will be reported as “not ready,” and thus, the vehicle will not be allowed to pass the I/M OBDII emissions inspection. Furthermore, it is possible that through normal operation, all of the monitors in a vehicle may not be set to “ready.” Therefore, the EPA has suggested in its guidance on performing I/M OBDII emissions inspections that vehicles with model years of 1996–2000 should be considered ready if two or fewer of the non-continuous monitors are “not ready.” For 2001 and newer vehicles, one non-continuous monitor may be reported as “not ready.” Furthermore, in a few states, three monitors are allowed to be “not ready,” and the vehicle is still considered ready for the OBDII I/M emissions inspection.
As mentioned above, if a vehicle fails an I/M OBDII emissions inspection and is repaired, the OBDII memory will be cleared and monitors will be reset to “not ready.” Since the vehicle cannot pass an emissions inspection until only a few monitors of the OBDII system are reporting their status as “not ready,” the technician may instruct the vehicle operator to drive the vehicle for a period of time and then return so the technician can check to see if the vehicle is ready to be tested. Because the technician cannot tell the vehicle operator how long they should drive the vehicle to get it ready, and vehicle operators are not pleased to return for an inspection only to discover that too many monitors are still reporting their status as “not ready,” there is a need for a device that can communicate to and notify a vehicle operator that a vehicle is ready for an I/M OBDII emissions inspection.